Introduce FieldIndex to unify and abstract property/field offset

src/string-stream.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/string-stream.h"
 
 #include "src/handles-inl.h"
 
 namespace v8 {
 namespace internal {
@@ skipping 330 matching lines @@
           len = String::cast(key)->length();
         }
         for (; len < 18; len++)
           Put(' ');
         if (key->IsString()) {
           Put(String::cast(key));
         } else {
           key->ShortPrint();
         }
         Add(": ");
-        Object* value = js_object->RawFastPropertyAt(descs->GetFieldIndex(i));
+        FieldIndex index = FieldIndex::ForDescriptor(map, i);
+        Object* value = js_object->RawFastPropertyAt(index);
         Add("%o\n", value);
       }
     }
   }
 }
 
 
 void StringStream::PrintFixedArray(FixedArray* array, unsigned int limit) {
   Heap* heap = array->GetHeap();
   for (unsigned int i = 0; i < 10 && i < limit; i++) {
@@ skipping 194 matching lines @@
 
 // Only grow once to the maximum allowable size.
 char* NoAllocationStringAllocator::grow(unsigned* bytes) {
   ASSERT(size_ >= *bytes);
   *bytes = size_;
   return space_;
 }
 
 
 } }  // namespace v8::internal